Investigation on Reactivity and Selectivity of Electrocatalytic CO₂ Reduction in Photochemically Synthesized Ag₁₉ and...

Atomically precise nanoclusters are desirable for understanding the structure-property relationships in the electrocatalytic CO₂ reduction reaction (eCO₂RR), but suitable related models are lacking, especially those of low- or zerovalent noble metal nanoclusters and their alloyed analogues. We first developed a photochemical method toward silver nanocluster Ag₁₉(4- ^t BuPhC≡C)₁₄(Dpppe)₃(SbF₆)₃ (Ag ₁₉ -2e) and then related copper-doped alloyed nanocluster Ag₁₂Cu₇(4- ^t BuPhC≡C)₁₄(Dpppe)₃Cl₃(SbF₆)₂ (Ag ₁₂ Cu ₇ -0e). Herein, we present a larger alloyed nanocluster, Ag₁₉Cu₂(4- ^t BuPhC≡C)₁₆(Dpppe)₄(SbF₆)₃ (Ag ₁₉ Cu ₂ -2e) and investigate the relationship between the structures and the eCO₂RR performance of those related nanoclusters. The UV-vis and mass spectra revealed that Ag ₁₉ Cu ₂ -2e forms via light-induced Ag ₁₉ -2e generation followed by Cu-(II) attachment. eCO₂RR tests showed that Ag ₁₉ -2e is the least efficient, while its dicopper alloyed Ag ₁₉ Cu ₂ -2e favors formate, highlighting the important role of copper doping in regulating Ag cluster catalysis. This conclusion is further confirmed by the good catalytic performance of Ag ₁₂ Cu ₇ -0e, which demonstrated the best C₁ product selectivity for both CO and formate. Experimental and theoretical calculations indicate that its excellent catalytic performance is attributed to the removal of Cl ligands, exposing active Ag sites for launching the eCO₂RR process. This work not only demonstrates that copper-doped silver nanoclusters significantly enhance catalytic activity but also reveals that varying copper doping levels enable modulation of product selectivity in eCO₂RR.